Testing FPGA and FPGA-based board interconnections

High-density FPGA-based boards are widely being used for logic development and verification before taping out the actual IC. On a high-density FPGA-based board where multiple FPGAs are interconnected with hundreds of signals, checking and validating the interconnections between the FPGAs becomes a very challenging task. This article describes how challenging the problem is and also suggests a simple, effective and generic solution to check the signal connectivity between the FPGAs. The method also helps the designer to identify and locate faults, if any, on the board which otherwise would have been a very cumbersome task. This article also proposes a method to efficiently generate the test code, most of which could be automated.

What is FPGA?
Short for Field-Programmable Gate Array, a type of logic chip that can be programmed. An FPGA is similar to a PLD, but whereas PLDs are generally limited to hundreds of gates, FPGAs support thousands of gates. They are especially popular for prototyping integrated circuit designs. Once the design is set, hardwired chips are produced for faster performance.